At present, some of the highly sensitive data information, e.g. bank information, password and registration key stored in the electronic circuit are frequently attacked and embezzled without authorization. Therefore, protection on these data is attached much more importance to than ever before. Various protecting devices and methods come into being. Among them, an effective method to protect the sensitive data against being attacked without authorization is to use software in memory device serving to store the sensitive procedure of encrypting and decoding or data to prevent the sensitive data from being embezzled. However, this method depends on the decrypting and decoding password, and the decrypting and decoding password also requires physical and electronic protection against being easily attacked.